GL.8
SEL-751 Relay Instruction Manual Date Code 20170927
Glossary
VT—Z-Number
VT
Abbreviation for voltage transformer. Also referred to as a potential
transformer or PT.
Vector Shift Element
The element is based on detecting phase shift (vector shift) in the three-phase
voltages caused by islanding of a generator and a subsequent sudden increase
of loading on the generator.
Wye
As used in this instruction manual, a phase-to-neutral connection of voltage
transformers for electrical measuring purposes. Three voltage transformers are
used with one primary lead of the first transformer connected to A-phase and
the other lead connected to ground. The second and third voltage transformers
are connected to measure the voltage from B-phase and C-phase-to-ground,
respectively. This connection is frequently called “four-wire wye,” alluding to
the three phase leads plus the neutral lead.
Z-Number
That portion of the relay RID string that identifies the proper ACSELERATOR
QuickSet SEL-5030 software relay driver version when creating or editing
relay settings files.
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